We have not the necessary space, even had we the necessary ability, to enter into a particular description of that rich and wonderful Japanese flora, which excites the imagination of the man of science as much as ever Japanese works of art in porcelain, bronze, and lacquer excited the imagination of the man of taste. We can only draw attention to a few striking facts and theoretical considerations, referring the reader for all details to Dr. Rein's masterly résumé of the subject, and to the works of Maximowicz, Savatier, Asa Gray, Sir Joseph Hooker, Itō Keisuke, and the other specialists whom Rein quotes.
The first impression made on any fairly observant person landing in Japan is the extraordinary variety of the vegetation. He sees the pine of the north flourishing by the side of the bamboo, or even of the tropical palmetto. A rice-field, as in India, stretches to his right; to his left will be a wheat or barleyfield, reminding him of Europe; or else he is overshadowed by some giant camphor-laurel, the like of which grows only in Formosa. Equally unexpected juxtapositions occur wherever he travels throughout the archipelago. No wonder that the number of known species of trees and plants (exclusive of mosses and other low organisms) attains to the enormous figure of 2,728, distributed over 941 genera and 151 orders while it is almost certain that further investigations will raise the figure considerably, the northern portion of the country having been as yet but imperfectly explored. Of forest-trees alone, Japan-or, to be strictly accurate, the Japanese region, which includes also Korea, Manchuria, and a portion of Northern China-possesses no less than 186 species divided among 66 genera, as against the 85 species in 33 genera of Europe. The Atlantic forest region of North America is nearly as rich as Japan, having 155 species in 66 genera. The Pacific forest region of North America is poorer even than Europe, having but 78 species in 31 genera. A further very curious fact is that North-Eastern America and Japan possess 65 genera in common. Evidently there must be some powerful underlying cause connecting phenomena at first sight so capricious. Dr. Rein lays great stress on the general similarity of climatic conditions obtaining in Eastern Asia and Eastern America, on the abundant rainfall of Japan, and on the convenient stepping-stones for vegetable immigrants formed by the Kurile Islands, Saghalien, Oki, Iki, the Luchuan archipelago, and other islands both to the west and south. May we not also accept Mr. Wallace's theory, as propounded in his charming book, Island Life, to the effect that the glacial epoch had great influence in bringing about the present state of things? When the climate of the north. temperate regions grew arctic, some of the trees and plants whose habitat was there must have perished, but others doubtless migrated in a southerly direction, where they could still find sufficient warmth to support their existence. In Europe, however, they were stopped-first by the barrier of the Alps, and then by the still more effectual barrier of the Mediterranean. On the Pacific slope of America, they mostly perished owing to the extreme narrowness of their habitat, which allowed of no free emigration in any direction. The conditions of Eastern America and of Eastern Asia were altogether different. Here were neither mountain ranges nor oceans to obstruct the southward march of the vegetation as it retreated before the ice; and when the ice had disappeared, all the heat-loving forms, safely preserved in the south, were able to return northward again, a considerable remnant of the richer vegetation of an earlier geological age being thus handed down to our own days in these two favoured regions.
A consideration to which little attention has hitherto been paid is the general identity of the Japanese flora with that of the adjacent coast of Asia. It is probable that when Korea shall have been thoroughly explored, not a few species now designated as japonica will be found to be really continental forms. It is already known that some of the plants now most common in Japan have been introduced in historical times through human agency. Such are, to name but two, the tea-plant and the orange-tree. The introduction of the latter is mentioned by the Japanese poets of the eighth century. The tea-plant came in with Buddhism. We were ourselves, we believe, the first to point out, some twenty years ago, the help which philology can give to natural science in this field, by proving that plants and also animals now inhabiting Japan, but originally imported from China or Korea, may often be detected in the Japanese language by their slightly corrupted Chinese or Korean names.
What we have for shortness' sake termed the Japanese region, is named by Rein "the north-eastern monsoon region," and is furthermore described by him as the "kingdom of magnolias, camellias, and aralias." It coincides very nearly in latitude with the region of the Mediterranean; but the character of the two is as different as can well be imagined. The Japanese region is the delight of the botanist. The Mediterranean region, with its severer forms and more sparing growth, better pleases the artist, who loves vegetation less for its own sake than as a setting for the works of man.
Books recommended - Rein Japan, pp. 135-174, is the best for the general reader.- Forest Flora of Japan, by C. S. Sargent.-See also Yatabe Iconographia Floræ Japonicæ, Savatier Enumeratio Plantarum and the same investigator's Botanique Japonaise-Maximowicz, Miquel, Satow, and others have written valuable monographs.